This invention relates to dispensing containers for storing and dispensing liquids such as milk, fruit juices, or other potables. Such containers may assume the form of the well-known gable top type milk container wherein access to the contents is obtained by spreading one end of the gable top apart to thereby form a pouring or dispensing spout, after which the spout is refolded until the next dispensing operation. Such containers may, alternatively, be provided with a pour spout, such as an injection molded plastic spout, having a flange at its bottom and having external screw threads for engagement with a screw on cap. For dispensing, the cap is removed, the container tilted, and all or part of the contents poured out through the pour spout. One example of such a container is shown in U.S. Pat. No. 4,483,464 issued to Nomura.
In a pour spout type container, such as shown in the Nomura patent, it is sometimes desirable to place a seal somewhere axially along the pour spout lumen or passageway, such as across a dispensing opening in the paperboard which forms the carton, with the opening being aligned with the pour spout lumen. In a construction of this type, it is known to employ a piercing insert which the user pushes down after the removal of the external screw cap, so as to rupture a seal or membrane which covers a dispensing opening in one of the container walls. This arrangement permits the contents of the package to be sealed and hence protected against contamination prior to the first use by the consumer. While performing the function of rupturing a seal membrane which covers the dispensing opening, such piercing inserts have not been completely satisfactory, either from a manufacturing point of view or because of difficulties encountered in their use.